The invention relates generally to a safety gate that is removably insertable into an opening such as a doorway. Such gates are used, for example, to prevent a child or a pet from passing through the doorway. More specifically, the invention relates to an adjustable-width, pressure-fit gate that is frictionally retained in the doorway opening by application of outward lateral force to the sides of the opening.
One type of conventional safety gate requires hardware to be mounted to the door frame sides to provide mounting points for the gate. For example, U.S. Pat. No. 4,884,614 to Spurling discloses a safety gate including a mounting rail attached to one doorway opening side and a locking post attached to the opposite doorway opening side. A hinged swinging door is mounted by inserting the hinged side of the door into the mounting rail. The door may be secured shut by locking the other side to the locking post.
The mounting hardware requirement imposes several disadvantages on this type of gate. Although it is often desirable to have a gate that is usable in many different openings, this conventional gate may only be used in openings where the hardware has already been installed. In addition, the hardware adds cost, is inconvenient to install, and is unsightly.
To overcome the foregoing problems of hardware-mounted gates, pressure-fit gates are known. These gates are frictionally retained in the doorway opening by application of an outward lateral force to the opening. For example, Great Britain Patent No. 2 193 992 to Alam discloses a generally U-shaped safety gate with a door. Four contact pads for securing the gate are each independently adjustable and apply outward pressure to frictionally retain the gate in the doorway.
This type of pressure-fit gate requires time consuming adjustment of each contact pad every time the gate is installed. This gate has a limited adjustment range and the adjustment also makes if difficult for the user to determine the amount of force being applied by each contact pad. Further, this gate is not seen to provide for convenient application of a repeatable and predictable outward force to retain the gate.
Another type of pressure-fit gate, described in U.S. Pat. No. 4,607,455 to Bluem et al., includes first and second gate sections that are adjustable relative to each other to adjust the overall width of the gate. One section includes a lever for rotating a gear wheel having teeth for engaging a rack of gear teeth on the other section to spread apart the sections. The lever has a non-engaging position so that the sections may be freely moved relative to each other to provide coarse adjustment of the gate width. Once the width has been adjusted to an overall width slightly less than the doorway opening, the gears are engaged and the lever is rotated to spread apart the sections. The sections are thus pressure-fit into the doorway opening
This type of pressure-fit gate suffers from several disadvantages. Since the outward pressure force is distributed throughout the gate panels, it is difficult to provide an opening or walk-through portion in the gate. The distribution of force throughout the gate panels also may result in undesirable warping of the gate panels under the load. In addition, it is difficult to adjust the relationship between the pressure applied to the doorway opening sides near the top of the gate and the pressure applied to the doorway opening sides near the bottom of the gate. Applying a greater pressure force near the top of the gate may be desirable where it is anticipated that the greatest side loads on the gate are likely to be applied near the top, for example by a child leaning against the top of the gate.
This type of gate also does not compensate for an out-of-square doorway opening, such as in the situation where the distances between the sides of the opening are different at the top and bottom contact portions of the gate. These variations in the doorway width can occur where the doorway sides are out of plumb or be caused by the presence of baseboard moulding near the floor. In a gate such as the one described in the Bluem et al. patent, the relationship between the top and bottom pressures is affected by differences between the top and bottom widths of the opening--a relatively greater pressure will be applied at the location where the doorway is narrower.
Also, since the starting point for the geared system is necessarily always relative to a gear tooth, each of the possible actual starting positions for expansion of the gate are spaced apart by a distance corresponding to the gear pitch. Thus, this system provides only an incrementally variable--not continuously variable--range of starting points. However, since the range of possible doorway opening widths is continuously variable, the gate starting point may vary relative to the doorway width for different doorways. When the gate starting point varies relative to the doorway opening as in the Bluem, et al. gate, the displacement of the panels, and hence the final force applied to the opening, after rotating the lever by a specific amount, will also vary. Consequently, this type of gate does not conveniently apply a repeatable and predictable force across a varying range of door openings.
Another type of pressure-fit gate is disclosed in U.S. Pat. No. 4,944,117 to Gebhard et al., in which two gate panels are slidably connected for width adjustment and are then secured together by a thumbscrew. Depressing a foot pedal on one panel moves a mechanical system to extend a pair of contact pads outward from one panel against the doorway opening side to frictionally retain the gate. A ratchet in the mechanical system locks the contacts pads in the outward position.
This gate also suffers from the disadvantages associated with the outward pressure force being distributed throughout the gate panels. Further, this mechanical system also fails to conveniently apply a repeatable and predictable outward lateral force to the pads.
Yet another type of pressure-fit gate is disclosed in U.S. Pat. No. 5,052,461 to Stern. This gate includes two panels that are extendable relative to each other to provide doorway width adjustment. After adjustment, the panels are secured together. Spring-biased upper and lower plungers mounted to one panel apply pressure contact to one side of the door opening to frictionally retain the gate. A handle is manually operable to retract the plungers for removal of the gate.
This type of gate also suffers from several disadvantages. The spring members and plungers occupy a large area in the door panel, making a walk-through gate difficult to achieve.
Still other types of pressure-fit gates are known in which levers are operated to extend the width of the gate so that it applies outward lateral pressure on the doorway opening. For example, U.S. Pat. No. 3,163,205 to Gottlieb discloses a gate supported by upper and lower telescoping rods, each having a lever mechanism provided at the telescoping connection. Once the gate is approximately fit into the opening, the levers on each rod are operated to engage and elongate each rod to apply the outward pressure. The levers each move a toothed catch that engaged a rack section on the telescoping rod to enter the rod. In another example, U.S. Pat. No. 2,928,146 to Kunihelm discloses a door gate having a lever arm that is pivoted to urge an upper bumper outward to pressure-fit the gate. A linkage connected to the lever arm also urges a lower bumper outwards when the lever is pivoted.
These gates also are not well suited to the provision of a walkthrough opening, since they include a top member spanning across the width of the gate.